AIR-GROUND COMMUNICATION FAILURE
Action by air traffic control units when unable to maintain two-way communication with an aircraft operating in a control area or control zone shall be as outlined in the paragraphs which follow.
As soon as it is known that two-way communication has failed, action shall be taken to ascertain whether the aircraft is able to receive transmissions from the air traffic control unit by requesting it to execute a specified manoeuvre which can be observed by an ATS surveillance system or to transmit, if possible, a specified signal in order to indicate acknowledgment.
If the aircraft fails to indicate that it is able to receive and acknowledge transmissions, separation shall be maintained between the aircraft having the communication failure and other aircraft, based on the assumption that the aircraft will: a. If in visual meteorological conditions:
1. continue to fly in visual meteorological conditions;
2. land at the nearest suitable aerodrome; and
INTERNATIONAL CIVIL AVIATION ORGANIZATION – AIR TRAFFIC MANAGEMENT 912 AIR TRAFFIC MANAGEMENT (DOC 4444)
3. report its arrival by the most expeditious means to the appropriate air traffic control unit; or
b. If in instrument meteorological conditions or when conditions are such that it does not appear feasible to complete the flight in accordance with a.:
1. unless otherwise prescribed on the basis of a regional air navigation agreement, in airspace where procedural separation is being applied, maintain the last assigned speed and level, or a minimum flight altitude if higher, for a period of 20 minutes following the aircraft’s failure to report its position over a compulsory reporting point and thereafter adjust level and speed in accordance with the filed flight plan; or
2. in airspace where an ATS surveillance system is used in the provision of air traffic control, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 7 minutes following:
i. the time the last assigned level or minimum flight altitude is reached; or ii. the time the transponder is set to Code 7600 or the ADS-B transmitter is set to indicate the loss of air-ground communications; or iii. the aircraft’s failure to report its position over a compulsory reporting point; whichever is later and thereafter adjust level and speed in accordance with the filed flight plan;
3. when being vectored or having been directed by ATC to proceed offset using RNAV without a specified limit, proceed in the most direct manner possible to rejoin the current flight plan route no later than the next significant point, taking into consideration the applicable minimum flight altitude;
4. proceed according to the current flight plan route to the appropriate designated navigation aid or fix serving the destination aerodrome and, when required to ensure compliance with 5, hold over this aid or fix until commencement of descent;
5. commence descent from the navigation aid or fix specified in 4. at, or as close as possible to, the expected approach time last received and acknowledged; or, if no expected approach time has been received and acknowledged, at, or as close as possible to, the estimated time of arrival resulting from the current flight plan; 6. complete a normal instrument approach procedure as specified for the designated navigation aid or fix; and
7. land, if possible, within 30 minutes after the estimated time of arrival specified in 5. or the last acknowledged expected approach time, whichever is later. NOTE: As evidenced by the meteorological conditions prescribed therein,
a. relates to all controlled flights, whereas
b. relates only to IFR flights.
15.3.4 Action taken to ensure suitable separation shall cease to be based on the assumption stated in
15.3.3 when: a. it is determined that the aircraft is following a procedure differing from that in 15.3.3;
or INTERNATIONAL CIVIL AVIATION ORGANIZATION – AIR TRAFFIC MANAGEMENT 913 AIR TRAFFIC MANAGEMENT (DOC 4444) b. through the use of electronic or other aids, air traffic control units determine that action differing from that required by
15.3.3 may be taken without impairing safety; or c. positive information is received that the aircraft has landed.
15.3.5 As soon as it is known that two-way communication has failed, appropriate information describing the action taken by the air traffic control unit, or instructions justified by any emergency situation, shall be transmitted blind for the attention of the aircraft concerned, on the frequencies available on which the aircraft is believed to be listening, including the voice frequencies of available radio navigation or approach aids. Information shall also be given concerning: a. meteorological conditions favorable to a cloud-breaking procedure in areas where congested traffic may be avoided; and b. meteorological conditions at suitable aerodromes.
15.3.6 Pertinent information shall be given to other aircraft in the vicinity of the presumed position of the aircraft experiencing the failure. 15.3.10 If the aircraft has not reported within thirty minutes after: a. the estimated time of arrival furnished by the pilot; b. the estimated time of arrival calculated by the ACC; or c. the last acknowledged expected approach time; whichever is latest, pertinent information concerning the aircraft shall be forwarded to aircraft operators, or their designated representatives, and pilots-in-command of any aircraft concerned and normal control resumed if they so desire. It is the responsibility of the aircraft operators, or their designated representatives, and pilots-in-command of aircraft to determine whether they will resume normal operations or take other action.